Waterproof shoe

ABSTRACT

An improved waterproof shoe incorporates several improvements. All layer-edges are connected to a net-typed insole. Neighboring layers are glued together to reduce leaking tunnels formed by crinkles therebetween. An ethylene vinyl acetate with a broad melt transition is added as a spacer to ensure sufficient injection spaces. Net-typed material is used for the material insole to ensure tension stress and mesh size. A water-absorbent and durable lining is added inside the waterproof functional layer to protect the functional layer from the damage by foot. Different materials are used for the sole to distinguish an inner sole which has the best injecting character and an outer sole which is commonly used for touching the ground.

FIELD OF THE INVENTION

This invention relates to a waterproof shoe, and more particularly, to such a shoe having an upper portion, an insole and a sole. The attachment of the components results in the waterproof character.

BACKGROUND OF THE INVENTION

Waterproof shoes are very popular in normal life. Many patents have been granted for waterproof shoes. One of them is U.S. Pat. No. 5,628,127 which was filed on Apr. 11, 1995. It is well known that a waterproof shoe must be made of waterproof materials, but waterproof materials of each part (the upper portion, the insole and the sole) must be attached to each other. For example, the upper portion must be attached on the sole, etc. Thus, leakage is prone to take place on these jointing places. At the beginning, many related prior art patents used waterproof glue to fill all jointing gaps. This is an inefficient process and the result was not very effective. Then, it was proposed to use an injecting process to attach all components (the upper portion, the insole and the sole) together by a single operation. Said U.S. Pat. No. 5,628,127 also adopted this single operation injecting process.

The inventor of this patent application substantially followed the teaching of U.S. Pat. No. 5,628,127 to produce 60 samples for testing, but alas, 57 samples leaked under certain test conditions. The high failure rate caused the inventor to conclude that U.S. Pat. No. 5,628,127 was unpractical for certain applications and caused the inventor to search for improvements.

The disclosure of U.S. Pat. No. 5,628,127 was analyzed. Only the lower edge 27 of functional material layer 15 was embraced in the injecting material 23 (See FIG. 1 of said U.S. Pat. No. 5,628,127).

There is no means to ensure space between the perforated insole 17 and the bottom 33 of the last 25. So, in practice, the perforated insole 17 will touch bottom 33 of the last 25 by the tension stress of the perforated insole 17, and the lower edge 27 of functional material layer 15 is in a free state and can crinkle freely in the injection process. The tunnels caused by the crinkle will form water leakage from the outer surface of functional material layer 15 to the inner surface of functional material layer 15 (See FIG. 1 of U.S. Pat. No. 5,628,127).

There is adhesive 31 between the outside of lower edge 27 of functional material layer 15 and the inside of the lower portion of upper material edge 19. However, since both of the upper material edges 19 were pulled by the perforated insole 17 while both of the lower edges 27 of functional material layer 15 have nothing to pull with, therefore, both of the lower edges 27 can be easily torn down from the adhesive point and crinkled. Consequently, a leakage will likely take place.

SUMMARY

Briefly stated, the improved waterproof shoe results from one or more features such as:

1. The use ethylene vinyl acetate adhesive with a broad melt transition (“EVA Broad”) for ensuring sufficient space between the bottom of the last and the perforated insole. 2. The connecting of all of the outer layer and the inner layer together; therefore, no free edges exist. Any force acting on edges of one layer will be resisted by all layers. 3. The use of net type material instead of perforated material for ensuring strength and mesh size.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the prior art construction shown in U.S. Pat. No. 5,628,127;

FIG. 2 is a sectional constructional view of a first embodiment of the waterproof shoe (before injection);

FIG. 3 is a sectional constructional view of a first embodiment of the waterproof shoe (after injection);

FIG. 4 is a sectional constructional view of a second embodiment of the waterproof shoe (before injection); and

FIG. 5 is a sectional constructional view of a second embodiment of the waterproof shoe (after injection).

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present improved waterproof shoe can best be described by initially referring to the prior art. FIG. 1 is the prior art construction shown in U.S. Pat. No. 5,628,127 Firstly, in this drawing, lower edge 27 of functional material layer 15 is in a free state. No means was apparently used to keep it in position. So, in the injection process, it will tend to crinkle and form leakage tunnels.

Secondly, there was apparently no means used to keep the perforated insole 17 in position. In practice, it can abut the bottom 33 of the last 25 by its own tension. Therefore, the space between the perforated insole 17 and the lower edge 27 of functional material layer 15 may not exist in practice. The tendency is that the lower edge 27 is pushed by the perforated insole 17 to abut the bottom 33. No space may exist on either side of the lower edge 27. The injecting plastic can not enter so narrow a gap to embrace the perforated insole 17.

Thirdly, the adhesive region 31 may be too small. The lower edge 27 can be easily torn down from the adhesive region 31. Therefore, leakage takes place along the outer surface of the lower edge 27 to the inner surface of the lower edge 27.

FIGS. 2 and 3 are respectively each a sectional constructional view of the first embodiment of an improved waterproof shoe before and after injection. In these drawings, certain parts corresponding to prior art parts represented in FIG. 1 use the same number with an additional lead digit.

The functional layer 115 is now completely glued on the upper material layer 113. The two layers 115 and 113 are then connected with the net-type insole 117. In doing so, since both layers are crinkled together, no leaking tunnel will be formed between the two said layers.

A hot melt adhesive such as ethylene vinyl acetate with a broad melt transition (“EVA Broad”) 51 is added. It acts as a spacer for ensuring there are sufficient spaces on both sides of the two layers.

A net-type material 117 is employed instead of perforated material for ensuring sufficient tension stress and mesh size.

A water-absorbent and durable material lining layer 18 is added for protecting the functional layer 115 from damaged caused by the foot, particularly a nail.

Different materials are used to distinguish the inner sole 123′ and the outer sole 123. In doing so, the inner sole 123′ can use a best material for perfect injecting. That is, the injected material can fill any tiny gap and be durable, for raising the waterproof feature of the shoe. The outer sole 123 can use any material commonly used for engaging the ground.

With reference to FIGS. 4 and 5, each is a sectional constructional view of second embodiment of an improved waterproof shoe before and after injection, respectively. The principal difference between these drawings and FIGS. 2 and 3 is that two net-type insoles 217 and 217′ are used. In these drawings, all three layers are connected to the net-type insole 217 and 217′. Since the thickness and hardness of each layer is different, in FIG. 1, the lining layer 28 is not connected to the insole 217, so it may be separated from the functional layer 215 in wearing. In FIGS. 4 and 5 drawings, both lining layer 28 and functional layer 215 are glued together and then connected to the insole 217′, while the upper layer 213 is connected to insole 217. In doing so, the leakage chance will be smaller than the first embodiment since the edge of water soaked upper layer 213 is now far separated from the edge of functional layer 215.

After employing the described improvements, waterproof shoes were constructed and tested. The percentage of successfully tested shoes was raised from 5% to 99% in comparison to a represented shoe as described constructed according to U.S. Pat. No. 5,628,127. 

1. An improved waterproof shoe comprising: an upper layer; a waterproof functional layer glued to said upper layer; an insole layer comprising a net-type material, said upper layer and functional layer connected at end portions to the insole layer; a water-absorbent and durable lining adjacent the waterproof functional layer; a spacer comprising EVA Broad to ensure sufficient injection spaces; and a sole formed of injected material combining together said upper layer, functional layer, insole layer and spacer and comprising different materials to distinguish an inner sole and an outer sole.
 2. An improved waterproof shoe as in claim 1, wherein said sole comprises two layers. 